He creado algunos campos de texto desde los cuales quiero usar la entrada del usuario. He leído que debo usar un documentlistener, pero creo que tengo algunas dificultades para implementarlo en el lugar correcto.

En el código estoy intentando implementarlo en el campo de texto tf1. La entrada que debo obtener es analizada a doble para que pueda hacer un cálculo matemático en ella.

Aquí está mi código donde intento implementarlo.

import java.awt.ComponentOrientation;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;


public class Display {
final static boolean shouldFill = true;
final static boolean shouldWeightX = true;
final static boolean RIGHT_TO_LEFT = false;

public static void addComponentsToPane(Container pane) {

    if (RIGHT_TO_LEFT) {
        pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
    }
    JButton button;
    JLabel label;

    pane.setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();
    if (shouldFill) {
    //natural height, maximum width
    c.fill = GridBagConstraints.HORIZONTAL;
    }
    if (shouldWeightX) {
    c.weightx = 0.5;
    }

    ...

    button = new JButton("Value Bet");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipady = 0;
    c.gridx = 0;
    c.gridy = 1;
    pane.add(button, c);
    button.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent e)
        {
            //Execute when button is pressed
            JFrame frame = new JFrame("Value Bet");
            frame.setVisible(true);
            frame.setSize(500,300);
            GridBagLayout layout = new GridBagLayout();
            frame.setLayout(layout);
            GridBagConstraints c = new GridBagConstraints();

            JLabel label;
            JTextField tf;

            if (shouldFill) {
            //natural height, maximum width
            c.fill = GridBagConstraints.HORIZONTAL;
            }
            if (shouldWeightX) {
            c.weightx = 0.5;
            }

            ...

            final JTextField tf1 = new JTextField();
            c.fill = GridBagConstraints.HORIZONTAL;
            c.gridx = 1;
            c.gridy = 2;
            frame.add(tf1, c);

            tf1.getDocument().addDocumentListener(new DocHandler(){
                public class DocHandler implements DocumentListener{

                    @Override
                    public void changedUpdate(DocumentEvent arg0) {
                        tfHasChanged();

                    }

                    @Override
                    public void insertUpdate(DocumentEvent arg0) {
                        tfHasChanged();

                    }

                    @Override
                    public void removeUpdate(DocumentEvent arg0) {
                        tfHasChanged();

                    }

                }

                public void tfHasChanged(){
                    double chance1 = Double.parseDouble(tf1.getText());
                }
            });      

            ... div components


}

 private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("Betting Application");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Set up the content pane.
        addComponentsToPane(frame.getContentPane());

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

 public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}